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Interplanetary Lyman-alpha observations with UVS on Voyager - Data, first analysis, implications for the ionization lifetimeA fraction of the measurements of the interplanetary Lyman-alpha background collected by the Ultraviolet Spectrometer during the cruise of Voyager 1 and 2 between 1977 and 1983 is presented and compared with results from current models of the interaction between the sun and the neutral interstellar gas. An analysis of two sets of data indicates that the same H atom lifetime cannot fit all the data. The actual ionization rate is inferred from the intensity gradient in the maximum emissivity region observed from a sidewind Voyager position at 6 AU, yielding a lifetime of about 1 exp 6 s at 1 AU, whereas the upwind/downwind intensity ratio in the inner solar system favors 2 x 10 exp 6 s, as measured by Voyager, Prognoz, and Pioneer Venus instruments. It is proposed that there is an excess of Ly-alpha emission in the downwind region which forces the model toward excessively high values of the lifetime. Possible explanations are discussed, like incorrect modeling or an additional source of H atoms.
Document ID
19920036375
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Lallement, R.
(Centre National de la Recherche Scientifique Verrieres-Le Buisson, France)
Bertaux, J. L.
(Centre National de la Recherche Scientifique Verrieres-Le Buisson, France)
Chassefiere, E.
(CNRS Service d'Aeronomie, Verrieres-le-Buisson, France)
Sandel, B.
(Arizona, University Tucson, United States)
Date Acquired
August 15, 2013
Publication Date
December 1, 1991
Publication Information
Publication: Astronomy and Astrophysics
Volume: 252
Issue: 1 De
ISSN: 0004-6361
Subject Category
Astrophysics
Accession Number
92A18999
Funding Number(s)
CONTRACT_GRANT: JPL-957763
CONTRACT_GRANT: NAS7-918
Distribution Limits
Public
Copyright
Other

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